This relates generally to image sensors and, more particularly, to image sensors having lenses to focus light.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an electronic device is provided with an array of image pixels arranged in pixel rows and pixel columns. Each image pixel in the array includes a photodiode that is coupled to a floating diffusion region via a transfer gate. Each pixel receives incident photons (light) and converts the photons into electrical signals. Column circuitry is coupled to each pixel column for reading out pixel signals from the image pixels. Image sensors are sometimes designed to provide images to electronic devices using a Joint Photographic Experts Group (JPEG) format.
Conventional image sensors sometimes include a color filter element and a microlens above each pixel. The microlenses of conventional image sensors typically have curved surfaces and use refraction to focus light on an underlying photodiode. However, these types of microlenses may not focus all incident light onto the intended photodiode, leading to optical cross-talk.
To prevent optical cross-talk, conventional image sensors sometimes include light blocking structures. However, these types of structures are large in size, difficult to manufacture, and have limited performance.
It would therefore be desirable to provide improved arrangements for microlenses and image sensors to reduce cross-talk and improve image sensor performance.